1. Field of the Invention
The present invention relates to an oil submersible pump.
In order to extract crude oil from non-flowing oil wells, special production equipment must be used. There are mainly two kinds of such equipments widely used at present: one is the piston-type oil extractor, the other is the oil submersible pump. Besides the use of extracting crude oil when submerged into oil wells, the oil submiersible pump can also be used for transferring water or other liquids.
2. Description of the Prior Art
The oil submersible pump applied in practice generally consists serially of multiple single-stage pumps with the same configuration. A typical single-stage pump is composed of two main parts namely, a rotable impeller and a stationary diffuser. The impeller is integrated by an impeller shroud as a collar rim, an impeller hub as a nave and circumferentialy equally spaced impeller blades therebetween. A driving motor rotates the impeller through a driving shaft to suck oil from an impeller inlet edge and discharge the suctioned oil through an impeller trailing edge, with the impeller being used for supercharging the fluid transferred. The diffuser is attached to the same shaft as the impeller on the impeller outlet side, being integrated by a diffuser shroud, a diffuser hub and equally spaced diffuser blades therebetween. The diffuser acts, firstly, to introduce the fluid out of the former stage impeller into the next impeller inlet and, secondly, to transform the kinetic energy of the fluid obtained from the impeller into static pressure energy.
The oil submersible pumps in prior techniques are mainly represented by type N-80 produced by Centrilife (Hughes) Company and type D-82 produced by Reda Pump Division (TRW) in the United States. The impeller blades and the diffuser blades of these conventional pumps are with the blade shape basically of the dimensional surface designed by using monadic flow theory, and the axial length of the impeller blade is much smaller than that of the nave, thus the relative velocity of the fluid at the impeller inlet being comparatively higher and the pressure gradient of the fluid in the impeller passages varying more intensively. The common disadvantages of these known pumps consist in lower hydraulic efficiency, lower head of a single stage, larger size of the contour, and so on.